Performance Evaluation of Cell Search Time for Heterogeneous Networks

This paper proposes local cell cluster-specific primary synchronization signal (PSS) sequence assignment and local cell-specific secondary synchronization signal (SSS) sequence assignment schemes for orthogonal frequency division multiple access (OFDMA) heterogeneous networks. The proposed synchronization signal (SS) sequences are based on those of the Long-Term Evolution (LTE) radio interface. We investigate the effects of the proposed SS sequence assignments from the viewpoint of the initial cell search time for various inter-cell site synchronization modes based on system-level simulations. We show that the local cell cluster-specific PSS sequence assignment achieves fast cell search time performance that is almost the identical level to that assuming the cell arrangement with a macrocell only. We show, however, that the effect of the new local cell-specific SSS sequences based on cyclic-shifted M-sequence in addition to the current 168 SSS sequences is small from the viewpoint of reducing the initial cell search time.